A Gecko-Like/Electrostatic Gripper for Free-Flying Perching Robots

This paper describes the experimental evaluation of a robotic gripper's ability to perch on a variety of flat surfaces when used in conjunction with a free-flying robot in microgravity. The gripper is designed to be integrated with Astrobee, a free-flying robot deployed in the International Space Station (ISS) in April 2019. Astrobee was developed to help astronauts perform routine tasks while aboard the ISS. The robot has physical space for payloads such as a manipulator arm, which allows it to grasp grapple points such as handrails to conserve energy while maintaining a given position. However, grapple points are not always readily available. As such, the goal of this work is to have Astrobee perch onto other surfaces. To enable extended perching times, the gripper described here uses a gecko-like/electrostatic adhesive coupled with a cam-actuated mechanism designed to consume little to no energy while engaged with a surface. The gecko-like adhesives allow the gripper to easily attach and detach to/from surfaces through the camactuation mechanism. The gripper was tested in a simulated microgravity environment where it was mounted on a platform equipped with air bearings. This paper describes the gripper design and evaluates the gripper's attachment performance as a function of the platform's approach velocity and approach angle for several different target material types. The gripper perched on glass and acrylic substrates with over a 70% success rate. For carbon fiber/epoxy laminate and Kapton sheets the success rate was approximately 50%. The results showed a clear correlation between the approach velocity and approach angle for carbon and glass materials.